Servo-programmed cable railway

ABSTRACT

A transportation system having a cable support means, a car carried on the cable, a means for generating a guidance signal relative to a reference path of travel, and means responsive to the signal for acting upon the suspension means to maintain the travel of the car in a selected course.

United States Patent n91 Scherbatskoy [1 1 3,759,185 1 Sept. 18, 1973 SERVO-PROGRAMMED CABLE RAILWAY [76] Inventor: Serge A. Scherbatskoy, 427 Wright Bldg, Tulsa, Okla. 74103 [22] Filed: Dec. 3, 1970 [21] Appl. No.; 94,858

Related US. Application Data [63] Continuation-impart of Ser. No. 847,530, July 31,

1969, abandoned.

[52] U.S. Cl 104/112, 104/114, 105/149 [58] Field of Search 105/149; 280/124 R,

I [56] References Cited 7 v UNITED STATES PATENTS 3,361,080 1/1968 Born et al. 104/114 ELECTR/CALLY c0/v/vcr0 CABLE 3567 ELECTR/CALL Y CONNECTED CABLE 35 3,538,855 ll/1970 St Cyr 104/173 3,479,471 11/1969 Smith et a1 191/45 R 413,389 10/1889 Cruikshank 4. 105/149 553,577 1/1896 Dickinson 104/115 2,636,290 4/1953 Bell 280/61 X 3,661,090 5/1972 Martin et al. .1 104/117 Primary ExaminerGerald M. Forlenza Assistant ExaminerGeorge H. Libman A!t0rneyCarl H. Johnson and Jam'es'R. Head [57] ABSTRACT A transportation system having a cable support means, a car carried on the cable, a means for generating a guidance signal relative to a reference path of travel. and means responsive to the signal for acting upon the suspension means to maintain the travel of the car in a selected course.

11 Claims, 24 Drawing Figures PATENTED 3. 759 ,185

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SERGE A. SCHERBATSKOY SERVO-PROGRAMMED CABLE RAILWAY 'The present invention relates to elastically suspended transport vehicle systems and, more particu larly, to a system in which the vehicles are carried by an overhead track or wire. Specifically, the present invention is a continuation-in-part of my copending Application Ser. No. 847,530 filed on July 31, 1969 now abandoned in favor of the present application.

In most rapid-moving vehicles the concept of unsprung weight is important. A low unsprung weight usually results in a smoother ride. In conventional railroads the unsprung weight comprises most of the bogie or truckv on which the car rests and, also, part of the rail. The rail usually gives" a noticeable amount, and when a conventional railroad train passes, the rail can be seen to be depressed, sometimes several inches. The total unsprung weight in conventional railroad cars is quite large, and even in modern passenger coaches the unsprung weight is several tons. The railroad car springing is conventional and quite stiff. In terms of automobile engineering the train ride would be termed very hard," and the relative smoothness of the ride of a rapidly-moving train is achieved principally by very accurate laying of the rails. Certainly in most vehicles effort is made to reduce the unsprung weight in order to achieve a smooth ride, and in almost all cases the wheels are an inseparable part of the unsprung weight, and reduction has a definite limit.

wheels.

In my invention I do not spring the wheels but attach them to the vehicle substantially firmly, and the sprung part of the suspension system is the track itself, and in a favored embodiment an overhead track consisting of a wire or wires. Since in such an arrangement the wire is in tension, the maximum strength of steel can be achieved and the wire can be comparatively light. The pertinent section of the wire will be very much lighter than the several tons of truck in conventional railroad cars. The wire can be made so light that it can be allowed to vibrate up and down over large amplitudes, and frequent supports are not necessary. In fact, by proper engineering the support can be spaced one hundred feet or more if necessary. In any event, since the wire is comparatively thin, it is not unsightly and does not obstruct light and air. The supports can be spaced sufficiently far apart so that the railroad" is substantially invisible and certainly not ugly and not viewor light-obstructing.

DESCRIPTION OF THE VIEWS FIG. I is a diagram of one embodiment of the invention.

FIG. 2 shows a non-linear spring means which may be employed in one embodiment of the invention.

FIG. 3 is a diagram of a control system which may be employed in practicing the invention.

FIG. 4 is adiagram of the invention as employed in making a curve in the path of travel.

FIG. 5 is a diagrammatic elevational view of a support arrangement.

FIGS. 6a through 6d show diagrammatic elevational relationship between a pair of cables supporting a car in one embodiment of the invention.

FIGS. 7, 7a and 7b show the practice of the invention wherein two spaced cables are utilized with FIG. 7a showing particularly the arrangement for suspending the vehicle equipped with two axles and four wheels.

' bles vary.

.the weight of the FIG. 9 shows diagrammatically an arrangement for stabilizing the altitude of a vehicle by means of a servo system and a reference member or pilot cable.

FIG. 10 shows diagrammatically another arrangement for stabilizing the altitude ofa car by employment of a reference altitude.

FIG, 10A is a circuit diagram which may be employed with the embodiment of FIG. 10 and illustrates a manner in which electrical resistance of the cables V and shunt resistors act as a latter network to control the propagation of control signals generated by servo sensors.

FIGS. I1, 11A, and 11B illustrate diagrammatically an embodiment of the invention employing a reference path defined by a mechanism similar to sensors used for inertial guidance.

FIG. 12 illustrates diagrammatically an arrangement for employing high frequency electromagnetic induction coupling of signals emanating from the car to control the elevational positioning of cable supports as a means of maintaining the desired path of travel of the car.

FIG. 12A shows an arrangement for the cable supports as utilized in the embodiment of the invention illustrated in FIG. 12.

A feature in my invention is the provision of a suitable suspension for the overhead wire. FIG. 1 shows diagrammatically the arrangement. I designates the vehicle or car hung by grooved wheels 2. The wire (which in a preferred embodiment would consist of several parallel wires or cables) is desigated by 3. Numeral 4 designates supports (the supporting columns are not shown), and numeral 5 a special elastic suspension.

The exact properties of this suspension are important.

. .it has a so-called non-linear spring effect, i.e., it does not deflect in direct proportion to the force but rather the deflection is a non-linear function of the force. It can be shown that the tension in the wire 3 is a function of the weight of the car I and of the sag 6 and for small sags directly proportional to the weight of the car and inversely proportional to the sag.

For the small sags of the order that are considered here,theformular is:

1/4 W-L/s where F is the force longitudinally along the axis of wire 3, W is the weight of the car I, L is the distance between the supports 4 and s is the distance of the sag 6. Thus, for each car weighing 20,000 pounds, a support separation of feet and a sag of 5 feet, the tension in the wire is about 100,000 pounds. The wire, if made of high-grade steel, need have a cross section of but 1.5 square inches, and the weight of the effectively moving or vibrating section of wire is only about 200 pounds which corresponds to a sprung-to-unsprung weight ratio of about 100:] (the car having a weight of 20,000 pounds). This is a very much better ratio than that in railroad cars or in autombiles. We seen, therefore, that we have at least acceptable characteristics. Certainly the vehicle need not weigh 20,000 pounds but could be lighter, and the span need not be 100 feet but could be shorter. Good safety factors, therefore, can easily be achieved, and if two wires are used for the support, the design can be such that even if one wire were to rupture, the second would have enough strength to support the entire weight of the car.

The spring 5 requires special attention. As pointed out previously, it is a non-linear spring and is designed in such a manner that the vehicle will travel in a strictly horizontal line with no up and down movement whatsoever.

FIG. 2 shows how a non-linear spring having any'desired characteristic can be designed. 7 is a helical spring of conventional characteristics attached to a cam, so that the cam can rotate about the axis of the helix and the force of the helical spring resists the rotation of the cam. It is obvious that the cam can have any shape. The line 9 wrapped around and in a groove of the cam 8 is attached to the wire 3. I

It can be shown that with the proper non-linear function for the spring 5 of FIG. I, a strictly horizontal path can be maintained for the car 1. At slow speeds, the car will travel without any vertical displacements and strictly in a horizontal stable position with ideal comfort for the passengers. At very high speeds, the vertical motion of the wire 3 may become noticeable, but as I have pointed out, a sprung-to-unsprung ratio of about l00:l can provide a relatively comfortable ride. It is desirable to eliminate even the small discomfort and for that reason I provide a servo mechanism that is controlled by interconnection between the succeeding support points 4. Each succeeding support is electrically connected to its predecessor support by means of a control system such as shown in FIG. 3.

With reference to FIG. 3, the displacement sensor 10 measures the displacement of the cable and generates an electrical signal representing the displacement. This electric signal is delayed in delay network 12 suitably connected by an electric circuit shown diagrammatically as 11. The delayed signal is then transmitted by electric cicuit 13 to amplifier 14 and thence to servodrive 15 which can be, for example, similar to a device manufactured by General Electric Company and sold under the tradename Thrustor.

The servo and delay system computes the necessary displacement for a succeeding suspension and operates as follows: When the car approaches the point 16a of FIG. 3, the cable 3 deflects downwardly. The downward deflection is measured by sensor 10 and is translated into an electrical voltage the magnitude of which is proportional to the deflection. After suitable delay and computation, the electric signal is amplified and transmitted to the servo-device 15 which is arranged to lower the point 17a of the cable by an amount which is exactly a predetermined function of the displacement at the preceding support point so that the car travelling along the cable 3 will progress in a straight, horizontal line. In other words, the signal generated by the sensor from a preceding support point informs the succeeding support point of the imminent arrival of the car and this support point adjusts the vertical position of the cable so that the car will travel in a horizontal line and be neither raised nor lowered. Of course, the interconnection of the sensors and servos can be made more elaborate by interconnecting several in a forward and backward information exhange arrangement.

Another factor besides the elimination of vibration at high speeds is the maintenance of the same vertical clearance of the car for various loads, since at stops it would be inconvenient for the broading passgeners if the car were not exactly on the same level with the station platform (although, of course, a few steps would not constitute a prohibitive objection). In order to accomplish constant ground clearance, an auxilliary suspension spring can be adjusted, or the axis of the helical spring 7 shown in FIG. 2 can be rotated by a servocontrolled electric motor.

So far I have achieved a vibrationless travel in a straight, horizontal line. The degree of freedom from vibration is merely a matter of the accurate design and cost of the servo devices and of the springs and damping arrangements. The complexity of such a system may appear at first glane to be substantial, but when compared to the complexity of the modern airplane controls, it is not serious.

There now remains the problem of handling the curves, i.e., when the vehicle travelling in a horizontal direction over the earth must change its direction of travel in this horizontal plane. A simple solution is to locate direction changes so that they occur at the stops or stations so that the change occurs at very low speeds. This is not always possible, and, in such events, an alternative arrangement must be used. FIG. 4 shows an arrangement for a curve. FIG. 4 is a plan view, i.e., a birds-eye view. l7, 18, 21 and 22 are standard support pylons as described previously, i.e., the suspension support is directly over the cable. 19 and 20 are special supports for the curve, and it will be noted that they are located on a somewhat larger radius of curvature than that along which the cable is located. It is desired to have the vehicle travel the smooth-curve path shown by the dotted line 23 rather than the angular path of the cable 3. The support 19 includes an auxiliary support 19a and similarly the support 20 operates cooperatively with an auxiliary 20a. The action of each pair of supports is such that as the car approaches the curve, the cable 3 is moved in th horizontal plane in a manner such that the car will travel along the smooth curve.

FIG. 5 is an elevation view of the support pair 19, 19a (i.e., a view as seen when looking along Jhe axis of the cable with the ground below). In FIG. 5 the car 1 is supported by the cable 3 which, in turn, is supported by an essentially non-elastic wire 24a connected to the support 19a and a standard elastic servo-controlled suspension, shown diagrammatically as 24.. This servo suspension is connected to the fixed support 19. It must be noted that support 19 is somewhat outside the desired path of the car, and support 19a is located somewhat inside this path.

As the car 1 approaches this pair of supports, 19 and 19a, the suspension 24 extends and allows the car to drop in the standard manner, but as the car drops it is displaced towards the center of the curve so that the car is moved horizontally toward the center of the curvature and, thus, along the path corresponding to the dotted line shown in FIG. 4.

Thus I have shown how the car 1 can be made to travel at any speed and still maintain a strictly horizontal path, even through the cable is supported only intermittently, and that curves can be transversed smoothly.

At very high speeds some vibration may be encountered if the computer-controlled suspension is not in perfect balance. For example, at 200 m.p.h. and a 50- foot spacing between support posts, there can be a vibration at a frequency of about six periods per second. Since the sprung-to-unsprung weight ratio is of the order of I and the absolute maximum amplitude (in case of complete failure of the servo computer) of the cable motion would be feet, this would correspond (in view of the mass of the car 1 and the sprung-tounsprung weight ratio of 100) to an actual vibration of the truck 2 of only about one-half inch. Such a vibration is much less than encountered in automobile wheels or train wheels and is very easily eliminated by an auxiliary conventional spring and damper between the truck and the car as shown as 2a in FIG. 1.

Another problem of vibration is the possibility of intercommunication of cable motion from one section to another. At each support post, it is very important to include good damping means similar to a shock absorber in an automobile. Of course, the system normally is under complete control of the computercontrolled servo, and at all times no uncontrolled motion can occur. But, again, in case of failure or partial failure, problems can arise, and at very high speeds, the system must be fail safe.

Vibrations at the cable support positions will not usually occur becuase of the very close control of the motions by the computer-controlled servo. In order to provide extreme fail-safe features, a damping means can be provided to the cable by means of vanes or multiple inertia dampers, well-known in the art. These consist of a small weight loosely supported in a cylinder and provided with means for damping motion of the weight by a viscous liquid. Such devices are sometimes called mercury ballistics. Another and simple form of introducing control is by predecessor and successor weights.

The car I in FIG. 1 can be preceded and succeeded by auxiliary cars which can be empty or arranged to carry freight or other substance which is substantially indifferent to vibration. The cars preceding the car 1 will be of gradually-diminishing weight as they are loccated farther and farther away from car 1. Similarly, the cars succeeding the car I will have the same weight decrease as a direct function of the distance from the car I. The wire 3 of FIG. 1 is thus gradually lowered to the position of maximum deflection and then gradually allowed to rise back to the normal position of rest, and there will be no rapid release of force The problem of vibration, of course, does not arise unless the car I is moving at very high speeds. At low speeds there is no problem at all, and only at speeds of 200-to-400 m.p.h. does vibration become of any significance at all. It must be remembered that the allimportant factor is the lightness of the vibrating member: The steel wire 3. It is of extremely strong material, and its effective weight of only about 200 pounds their torque-vs-r.p.m. characteristic is not favorable. For moderate speeds in urban environments the electric motor has many advantages, since for these conditions only a small amount of continuous power is required. For acceleration probably not more than a few hundred horsepower is needed, and for continuous operation at moderate speeds, as little as horsepower could suffice. For urban use, electric motor power, coupled to the wheels of the truck of the car I, is preferable. Gasoline engines are, of course, very light, and weights as low as I pound per horsepower, or even lower, are being realized. The preferred arrangement, however, is electric motor propulsion with a two-wire suspension, each wire being an electric conductor for supplying power to the car.

I have described an embodiment of my invention by illustrating an arrangement in which the vehicle is suspended from an overhead track or cable. In some instances it may be preferable to have the vehicle travel over underlying support members or rails in which arrangement, of course, the underlying rails or members will be elastically supported by the springs an Servo devices similar to the one described. This arrangmeent may be advantageous in certain cases. Similarly it may sometimes be advantageous to provide support members or wires on each side of the vehicle instead of above or below it. In order to stabilize the travel several support members or cables may also be provided above and below the vehicle.

The cable railway system described in connection with FIGS. I through 5 is satisfactorily operable. In order to enhance further the precision of maintenance of the vehicle position, modifications in some instances may prove an advantage. These include:

a. Provision of two support cables and staggered support points. Thus, if the suspension members 5, of FIG. I, are not completely perfect in operation the staggered arrangement described in connection with FIGS. 6, 7 and 8 will eliminate or substantially reduce imperfection. Furthermore, the provision of two support cables givesthe opportunity for greater safety in case of rupture of one cable, and also gives opportunity for the provision of electrical power for the drive motors of the vehicle.

b. The provision of a reference path or pilot member." This pilot member can be in the form of a very tightly stretched cable which does not sag and is not required to support the vehicle weight, or can be in the form of an inertial guidance system or micro wave radio beam. The pilot path serves as a reference line for the purpose of generating a correction signal responsive to any departure of the vehicle position from the desired optimum.

With reference now more particularly to FIGS. 6 and 7: FIG. 6 represents an improvement in the arrangement of FIG. I. FIG. 6 is a diagrammatic and shows the arrangement in elevation,i.e., the line of sight of the observer parallel to the surface of the earth and at right angles to the direction of travel of the vehicle or car. Numerals 25 and 26 indicate members respectively corresponding to 4 and 5 in FIG. 1. For purposes of illustration the cable 28 (corresponding to cable 3 of FIG. I) is shown in an unloaded condition. Thus between the support points 25 the cable follows the conventional sag substantially along a series of catenaries. In addition to the cable 28 a second cable 29 is provided separated from 28 by a distance of several feet as shown by d in the plan view of FIG. 7. The second cable 29 is supported at the support points 27. 25, 27 are connected by rigid support columns to the earth. FIG. 7a shows (again in plan view) the vehicle or car 32 riding along the two cables 28 and 29 and suspended from two axles 33 and four grooved wheels or sheaves 30, 31 30a, 31a. FIG. 7b shows the view of the two cables along their axes with the vehicle or car 32 suspended from an axle 33 with the two grooved wheels or sheaves 30, 31 riding on the two cables 28 and 29 separatedby the distance d. For simplicity of illustration the diagrammatic FIGS. 7b, 8, 9, 10 show only one axle and one pair of grooved wheels. In a practical arrangement usually two or more axles 33 will be provided with the corresponding number of four or more grooved wheels.

When the vehicle is traveling along the cables 28 and 29 of FIG. 6 the suspension members 26 will yield as described earlier in this specification, and ideally the locus of the wheel contact points on the cables as the car travels along their length will be a straight horizontal line. In a practical case, where the suspension members 26 may be imperfect, the locus of the succeeding contact points on the cable 28 or 29 can be an undulating curve. FIG. 6a illustrates this curve when the suspension members 26 are out of adjustment in the soft direction, i.e., the members 26 elongate somewhat more than is ideal. FIG. 6b shows the reverse condition where the members 26 are out of adjustment somewhat towards a stiff condition and yield somewhat less than the ideal amount. It is to be pointed out that the curves of FIG. 6a and 6b are notcatenaries but are smooth curves. At the support points 25a and 27a sharp bends occur when the cables are not loaded by the car, but in the loaded condition the points follow a straight horizontal line when the suspension members 26 are in perfect adjustment and a smoothly undulating line as shown in FIGS. 6a and 6b when the adjustment of the members 26 departs from the ideal. FIGS. 6c and 6d show (in elevation) the paths of the car wheels 30 and 31 when the suspension members 26 are incorrectly adjusted: 60 when they are all too soft" and 6d when all are too stiff." In FIGS. 60 and 6d it can be seen that under load the supoort cables 28 and 29 depart from the ideal (a horizontal straight line) in opposite directions, i.e., under load, when one cable is too high the other is too low. This efiect is due to the staggering or alternation of the support points. FIG. 8 is a view along the axes of the support cables and illustrates how the effect of imperfections in the suspension members 26 is reduced when two separated support cables and staggered support points are employed. FIGS. 8, 8a, and 8b show the position of the car 32 as it progresses along the support cables. The car 32 is pivotedly attached to axle 33 which in turn is connected to the grooved wheels 30 and 31 in conventional manner. The wheels ride on the cables 28 and 29. The car 32 is suspended from pivot point 34 so that the force of gravity keeps the car vertically below point 34. It is seen from the successive illustrations 8, 8a, and 8b that even as the cables 28 and 29 depart from the ideal altitude as shown in the FIGS. 6c and 6d and the altitude of each individual cable above the ground varies, a compensation takes effect and the car 32 tends to remain at a constant altitude, i.e., at approximately the mean altitude of the two cables.

FIG. 9 illustrates an arrangement for stabilizing the altitude of the vehicle or car by means of a Servo system and a reference member or pilot cable. In FIG. 9, 28 and 29 are main support cables viewed along their axes; 35 indicates the pilot member or reference cable viewed along its axis. For clarity of illustration suspension members and the columns that hold the entire cable system above the terrain are not shown; it is assumed that the support cables 28 and 29 are held in the manner illustrated for the cable 3 in FIG. 1, i.e., by means of the elastic suspension members corresponding to 5 in FIG. 1, or 26 in FIG. 6. Pilot cable member 35 is supported rigidly, i.e., no elastic suspension members are provided. It is important that the pilot member 35, which can be either a very tightly stretched cable or a thin tube or small I-beam, be strictly horizontal (or at the desired slope in the case of sloping terrain). The support is not shown but since the pilot cable member 35 is not required to carry any load, the provision of a strictly fixed and constant altitude position can be accomplished without difficulty. In FIG. 9 the axle 33 joins the grooved wheels 30 and 31. A bearing 34 provides a pivoting capability so that the Servo system 36 and the car 32 are suspended below and maintained in a vertical position by gravity. The purpose of the Servo system 36 is to maintain automatically constant the altitude of the car 32 in spite of possible variation in altitude of the point 34. As mentioned previously the reference cable 35 is always at constant altitude; if there is a variation in the altitude of point 34 there will be relative displacement between points 34 and reference cable 35 and therefore relative displacement between point 34 and the arm 37 which holds the grooved wheel 37a resting on the reference cable. Motions of the arm 37 operate the valves of Servo system 36 in such a man ner that piston 38 is forced upwardly or downwardly to tend to keep the altitude of the car 32 a constant. Numeral 39 is a hydraulic pump that is continuously operated by a motor so that there is constant hydraulic fluid pressure in the tube 40, which pressure (p exceeds the pressure in the tube 41 (p At all times p is greater than p The entire space within hydraulic cylinders 42 and 43 is filled with hydraulic fluid. The operation of the Servo system 36 is as follows: In a normal position the pistons 44 are in the position shown in FIG. 9. The sleeve valves 45 and 46 are open and the sleeve valves 47 and 48 are closed. Piston 38 therefore receives upwardly and downwardly pressure in an equal amount and remains in the balanced condition. Assume now that because of an imperfection in the suspension members 26 of FIG. 6, one or both of the cables 28, 29 lowers and pivot point 34 and arm 49 therefore also lower. This lowering will momentarily tend to cause the car 32 and the cylinder of 36 to lower also. Thus arm 37 will tend to move upwardly relative to the Servo system 36. This upwardly displacement will move pistons 44 in a manner such that sleeve valve 46 will tend to close and sleeve valve 48 will tend to open while sleeve valve 45 remains open. The opening of sleeve valve 48 exposes the lower section of piston 38 to the lower pressure p, while the upper portion of piston 38 remains exposed to the high pressure p This forces piston 38 downwardly with respect to the main cylinder of 36, or corollarily forces the entire unit 36 and car 32 upwardly with respect to pivot point 34. Thus whenever point 34 lowers the Servo system of FIG. 9 tends to raise the car 32 and compensate the altitude change. Conversely should pivot point 34 and arm 49 rise, arm 37 will tend to lower with respect to 36. This lowering tends to close sleeve valve 45 and open sleeve valve 47 while sleeve valve 46 remains open. When this occurs the upper side of piston 38 is exposed to the reduced pressure p and the piston 38 tends to move in an up-' wardly direction with respect to 36 or corollarily, 36 and the car 32 tend to move downwardly with respect to pivot point 3 3 thus tending to lower the car and compensate for the altitude change of the cables 28 and 29.

With further respect to FIG. 9, the axle 33 is interrupted at the points 50 and electrical insulating material 51 is inserted to electrically insulate axles 33a from the axles 33. This arrangement makes it possible by means well known in the art to use the support cables 28 and 29 (which are electrically insulated one from the other) as a source of electrical power, either AC or DC. This electrical power can be used to drive grooved wheels 30, 31 of FIG. 9 in order to provide forward or backward propulsion to the whole assembly of FIG. 9 including the car 32 in a manner that is well understood by those skilled in the art.

FIG'. illustrates another arrangement for stabilizing the altitude of the car by employment of a reference altitude. In FIG. 10 numerals 35, 35a designate a pair of reference members which are either very tightly strung cables or rigid members as described previously. The altitudes of the reference cables 35 and 35a are strictly constant throughout their length. The mechanisms of FIG. 10 are similar to those of FIG. 9; however in FIG. 10 the altitudes of the main support cables are variably controlled whereas in FIG. 9 the distance between the support cables and the car 32 is variably controlled. In FIG. 10 the distance between the car and the support cables is constant and the control action is on the altitude of the support cables. The Servo-Sensor A makes a measurement of the distance of the car'32 from the reference cable 35 and transmits a signal indicative of this measurement to Servo-Drive B in a manner such as to maintain the distance between car 32 and reference cable 35 a constant. The Servo-Drive unit B of FIG. 10 is similar to Servo-Drive 36 of FIG. 9. Numerals on FIG. 10 correspond to like numerals on FIG. 9. Operation is as follows: The car 32 and Servo- Sensor A are electrically connected to a point designated on the figure as ground." This electrical ground is determined by the two equal resistors'R connected to the axles 33a. The midpoint of the resistors is electrically connected to axle 33 and arm 49 and the two other ends of the resistors are electrically connected to the axles 33a and to grooved wheels 30, 31 which in turn electrically connect to cables 28, 29. (At appropriate locations in the system the two sup port cables 28, 29 are also electrically connected to-a pair of resistors R ,R preferably of low ohmic value, and the resulting electrical midpoint connected to a stake driven into the earth.)

Servo-Sensor A is provided witha potentiometer 52 and two equal batteries 53. The Servo-Drive B is actuated by a solenoid 54 which can shift the arm 58 upwardly or downwardly. An electronic amplifier 54a is interposed between solenoid 54 and the electrical lead 55. Assume now that the car 32 tends to lower to a position below the desired altitude. This lowering action will lower the Servo-Sensor A with respect to arm 37 (which always has a constant altitude), the arm of the potentiometer 52 will therefore effectively more upwardly with respect to the resistance wire of 52, im pressing a negative DC voltage on cable 35. The moving arm of potentiometer 52 is electrically connected to cable 35 by arm 37 and grooved wheel 37a. This negative voltage will therefore also be impressed on lead 55 and, after amplification by 54a, impressed on solenoid 54. In the figure the Servo-Drive 1B is shown in a balanced position. The action of the solenoid tends to disturb this balance in a manner such that when negative voltage is impressed at lead 55 the pistons 44 are moved downwardly. This downwardly motion of the pistons 44 tends to close sleeve valve 45 and open sleeve valve 47, thus causing the high pressure p, to be in the chamber 42 below piston 38 and the lower pressure p to appear in the upper chambers 42a. This pressure differential causes the piston 38 to move in an upwardly direction and consequently to raise arms 57a and 57 and therefore raise cable 29, thus restoring the car 32 to the correct altitude. Conversely if car 32 rises Servo system A,B will lower cable 29. For completeness elastic members 26 are shown, but these are not always necessary.

In FIG. 10 the operation is described in connection with a Servo system comprising Servo-Sensor A and Servo-Drive B. In a simple arrangement both cables 29 and 28 can-be supported by a single arm (corresponding to 57) and the altitude of both cables 29 and 28 controlled by a single Servo-Drive (corresponding to B). As an alternate a second Servo-Drive B, identical to B, is provided and the electrical lead designated by 56 is connected directly electrically to the lead 55 and therefore to cable 35. In this arrangement the Servo- Drives B and B will both be commanded by the single Servo-Sensor A, Le, B and B will be connected in parallel and consequently the motions of the cables 28 and 29 will be in unison. An alternate and preferred arrangement is the connection of lead 56 electrically to reference cable 350. The second Servo-Sensor A, identical to A, is then employed. In this arrangement the Servo system A,B will operate independently of the Servo system A,B'. Variations in load distribution within the car 32, variations in the stretch characteristics of cables 28, 29, and variations stretch characteristics of cables 28, 29, and variations in the optionally includable suspension members 26 (corresponding to 5 in FIG. ll) can therefore be compensated for individually. FIG. 10 is diagrammatic. In an actual case the car 32 will usually be supported by the four heel bogie shown in FIG. 7a. It may be desirable to provide four Servo systems, one for each grooved wheel, but in many cases since the distance d on FIG. 7a is small two Servo systems will suffice.

A modification of the arrangement described in reference to FIG. 10 would consist of locking the swivel point 34, i.e., the member 49 and the axles 33 would be rigidly connected one to another as, for example, by welding. In such arrangement sway caused by wind or other disturbances will be minimized because the tendency to sway will be counteracted by the actions of the Servo-Sensors A and A and Servo-Drives B and B. Should the car 32 tend to move to the right in FIG. 10, Servo-Sensor A will become short and Servo-Sensor A will become long," each producing the proper counteractions in B and B, thus tending to eliminate sway. In this arrangement the staggering" of FIG. 7 may not be used.

In the arrangement illustrated in FIG. 10 resilient means are provided for control of the motion of arm 49 in relation to the axles 33. Numerals 58 indicate springs and numerals 59 indicate damping shock absorbers. Member 49 and the car 32 can swing on the pivot 34 but the motion is controlled. In this arrangement sway is minimized but the rocking action of the axle 33 described in connection with FIG. 8 can take place.

The Servo systems A,B described in connection with FIG. 10 are shown for illustrative purposes in order to explain as clearly as possible the principles of my invention. Details and certain features are not shown in the figures in order to simplify the presentation.

In FIG. 10 the electric voltage generated by the Servo-Sensors A,A would proceed along the entire length of the cables 35, 35a and thus actuate the Servo-Drives B,B' at all the support points along the entire length of the support cables. This could be disadvantageous and can be obviated by providing electrical shunt resistors R betwee the cables 35,35a to ground at each support point. The signal generated by the Servo-Sensors A,A' will thus diminish in magnitude with distance from the car 32. The resistance of each section of cables 35 and 35a behaves as the series resistances and the shunt resistors to ground behave as the shunt resistances of an electric ladder network. The signals generated by the Servo-Sensors A,A' will thus suffer attenuation as the distance from the support point to the car 32 increases.

FIG. 10a is the electrical circuit diagram of the system of FIG. 10 and illustrates the manner in which the electrical resistance of cables 35, 35a and the shunt resisors R act as a ladder network and attenuate the propagation of the control signals generated by the Servo-Sensors A,A'. In FIG. 100 the reference cables 35, 35a are shown as continuous electrical resistors. A and A are the Servo-Sensors and B and B are the Servo- Drives of FIG. 10. The ground is achieved by stakes driven into the earth and if necessary all interconnected by a copper wire buried in the earth. These grounds for the entire system are shown by the rectangular elements designated GROUND. The ground referred to in connection with the description of FIG. 10 is shown by the usual symbol used in electric diagrams and designated ground." Since the resistors R and R, are of low ohmic value, for all practical purposes the entire system has only one ground and the elements marked GROUND and the symbol ground" can all be considered equipotential. The various ele ments indicated by numerals on FIG. 10 are shown by like numerals on FIG. 100. It is seen that the series resistance of the cables 35, 35a and the shunt resistors R, will act as attentuators for the signal generated by the Servo-Sensors A, A and consequently the magnitude of the control voltage provided to Servo-Drive B, B will diminish as the distance of the car 32 increases from each support point. Also, since resistors R are present at each support point the behavior will be that of an electric ladder network and the attentuation of the control signal from A and A will increase rapidly with the distance of the car 32 from any given support point. In a variation in order to disable the control action where not required switching mechanisms could be provided that would disable all the Servo-Drives B,B along the entire length of the cable railway system with the exception of a selected number located at stations in the close vicinity of the location of the car 32. Simple Micro switches installed in units 26 of FIG. 10, for example, could be arranged to disconnect leads 55 and 56 when the load on cables 29 and 28 is below a certain predetermined minimum.

It sometimes can be inconvenient to provide strictly straight and horizontal reference cables 35 or 35a. Some sag can occur. In order to overcome the effects of sag a virtual" or image reference member can be achieved electronically and such virtual reference member will act substantially as a horizontal member and without sag. This electronic arrangement is accomplished by providing the additional resistor R shown in FIGS. 10 and 10a. This resistor couples the actions of Servo-Sensors A and A in a manner somewhat similar to the coupling by axle 33 in FIG. 8. When the supports of cables 35 and 35a are "staggered as is shown in FIG. 7 the resulting sags of cables 35 and 35a are analogous to the sags illustrated in FIG. 6. When one is low the other will be high. The electric crosscoupling caused by resistor R, will tend to provide a virtual reference member that will have an altitude equal to the average value of the altitudes of the cables 35 and 350.

I have illustrated some principles of my invention in connection with FIGS. 9 and 10 in order to explain the operation in clear and elementary fashion. The illustration of a reference path by use of reference mechanical cables 35, 35a is a convenient presentation.

More precise and satisfactory apparatus can be used to provide the measurement of variations in the course of the car 32 as it travels along the support cables 28, 29. Electronic terrain cleArance indicators and altimeters used in present day aircraft, narrow horizontal beams of microwaves, optical sighting, and instruments similar to inertial guidance devices can perform measurements that will define the reference path in space with very great accuray.

A preferred embodiment of my invention employs a reference path defined by a mechanism similar to a sensor used for inertial guideance and is illustrated in FIGS. 11, 11a, and 1 1b. Basically, inerital guidance employs an accelerometer than responds very accurately to acceleration (in the case of FIGS. 11, 11a the vertical component of acceleration). By integrating the output signal of the accelerometer one obtains velocity and by integrating a second time one obtains displacement. The measurement of acceleration and the performance of the integrations must be accurate and the acceleration due to gravity must be subtracted; in my invention this effect of gravity is a constant and subtraction is not difficult.

In my invention the signal generated by the inertial guidance sensor need not be as accurate as that required for a navigational aid of aircrafl or submarines that travel thousands of miles and for many hours or days between calibration points. In my arrangement in FIGS. 9 to 12 relatively rapid displacements of only a few feet are involved and the calibrations can be performed at frequent time and distance intervals by automatic means, as for example, at the stations or stops for the discharge and taking on of passengers.

Principally, inertial guidance is based upon the measurement of acceleration by measurement of the relative movement between a support member and a mass connected thereto by a suspension system, as for example, by a spring. FIG. 11 shows a simplified arrangement in which the departures from the reference path and the necessary correcting signals for the Servo- Drive B are provided by a seismometer comprising mass 63 suspended on a very long period suspension using a spring 65 and damping means 64. Numerals in FIG. II designate elements shown by like numerals in FIGS. 9 and It). Here the numbers 26 are not necessary but are shown for sake of completeness. The operation is as follows: The housing C and the resistance wire element of electric potentiometer 52 on insulation column 52a are connected rigidly to the car 32; the mass 63 is suspended by spring 65 and damping device 64, the upper ends of which are likewise rigidly connected to C and car 32.

Assume now that in FIG. 11 the car 32 and Servo Sensor C move downwardly, the mass 63 will tend to remain fixed in space and the arm of potentiometer 52 will effectively move upwards relative to the resistance wire element; this will produce a negative voltage at the flexible lead 62. By operation of the telemetering system (comprising, as will be explained later, modulator 66, radio oscillator 67, loops 60, 61, reference phase antennas 60b, 61b, amplifier 68 and demodulator 69) the arm 58 in Servo-Drive unit B will be forced downwardly and the cable support member 57 caused to move upwards in a manner similar to that described in relation to FIG. I0. Conversely, should the car 32 move upwardly the Servo-Drive B will tend to lower arm 57 again in a manner similar to that described in connection with FIG. 10. The course of car 32 is thus stabilized.

Although a telemetering system as shown in FIG i l is well known I will describe it briefly for sake of completeness of this specification: Modulator 66 and oscillator 67 provide phase sensitive modulation, i.e., when the electric input to 66 at lead 62 is zero the output of oscillator 67 to loop 66 is zero; when the input at 62 is a positive voltage the output of oscillator 67 will have phase and will increase as the positive voltage at 62 increases; when the voltage input to modulator 66 is a negative voltage the output of oscillator 67 will have phase l80 and the output will increase as the negative voltage at lead 62 increases. 60 and 61 are loops and are coupled one to another by conventional radio means; reference phase antennas 60b and 61b are provided to transmit the reference phase. Amplifier 68 is conventional. Demodulator 69 is a so-called synchronous demodulator (or synchronous rectifier) and is phase-sensitive, i.e.,- when the phase of the AC signal provided by amplifier 68 reverses the polarity of the DC voltage across leads 76a, 76b also reverses. The magnitude of the DC voltage at leads 70a, 70b is how ever proportional to the magnitude of the signal supplied by 68; thus if, for example, a positive voltage appears on lead 62 in Servo-Sensor C lead 700 will be positive with respect to b and conversely, if a negative voltage appears on lead 62, lead 70a will be negative with respect to lead 70b.

FIG lll is a simplified presentation. In practices servo-Sensor similar to C of FIG. 11 would usually be a sensing element based upon the principle of inertial guidance incorporating the process of double integration -of acceleration described previously. With such double integration of the acceleration much longer term stability can be obtained.

A servo-sensor containing an inertial guidance sensing element is shown in FIG. Illa. Housing V is rigidly fastened to car 311. Numeral 7Ia indicates a conventional gyro-stabilized platform, 71 indicates an accelerometer designed to provide an output directly proportional to the vertical acceleration of housing V, and therfore of the car 32. (The effect ofthe constant force of gravity is subtracted.) Numerals 72 and 73 designate integrators. The electric voltage at leads 74a, 74b (and therefore at transmitting loop is representative of the vertical position of housing V and therefore of car 32. In the arrangement of FIG. lIa the control action on Servo-Drive B is the same as in FIG. II, i.e., should car 32 tend to rise the signal generated by Servo-Sensor V will act upon Servo-Drive B in a manner to lower cable supprt member 57 and conversely, should the course of car 32 tend to lower in altitude the action of Servo-Sensor V and Servo-Drive B will raise cable support member 57. The vertical course of car 32 is thus stabilized and will follow the pilot reference path defined by the inertial guidance system 71, 72, 73.

FIG. 11b illustrates an arrangement employing inertia guidance sensors and Servo-Drives for control of both the altitude of the course and the transverse position of the course of the car 32. Two inertial guidance sensors are provided that are substantially identical to that of FIG. 11a. In FIG. 11b dotted rectangle V designates an inertial guidance Servo-Sensor identical to the one enclosed in block V of FIG. 11a. It measures the vertical component of the course of the car 32 and therefore is designed to control the vertical position or altitude of the car 32. Dotted bock T designates an inertial guidance sensor designed to measure the transverse component of the displacement of the car (transverse to the direction of travel). Serve-Drive B, controls the vertical position of cable 29 and B (connected to the suspension arm 57 by a relatively long arm 57:) controls the transverse position of the support cable 29. Like numerals in FIGS. 11, 11a, 11b designate like elements.

A two coordinate control system using Servo-Drive units 8,, B as illustrated in FIG. IIb can be used to control individually the position of each of two suspension cables. Thus as is shown in FIG. 12 each cable 28 and 29 is individually controlled in the vertical direction and the transverse direction.

Those skilled in the art will be aware that various telecommunication systems can be employed instead of the ones illustrated in FIGS. 9, 10, 11, 11a, 11b. Serve- Sensors A, C, V or T could, for example, incorporate arrangement for transmitting a frequency modulated carrier signal and Servo-Drive B could incorpoate a suitable FM detector. Other telecommunication systems are well known.

FIG. 12 illustrates diagrammatically the arrangement employing high frequency electromagnetic induction coupling. Servo-Sensors like T and V of FIG. 11b are located in the car 32 and actuate high frequency electromagnetic induction or radio coupling with the desired Servo-Drive units 13,, B and B,', B Transmitting electromagnetic loops 60, 60 on car 32 are arranged to couple to receiving loops 61, 61' located on the columns that hold the Servo-Drive units for the cables 28, 29. The angle of inclination of the loops can be adjusted so that electromagneti9 coupling between them will increase with the proximity of the car 32 to the Servo-Drive units in accordance with a predetermined and desired function. After the car 32 passes the four Servo-Drive units the electromagnetic coupling will decrease and when the car 32 is distant the coupling will be eliminated entirely, thus freeing the Servo-Drive units for action in response to a succeeding car which may have a weight different from the car that has just passed.

It should be noted that sometimes at the support pylons or colums 4 of FIG. 12 an excessive longitudinal pull can be exerted by the cables 28 and 29 in a direction along the axes of the cables. To obviate this disturbing effect on the columns or Servo-Drives the cable support 75 can be provided with a grooved support pulley as shown by numeral 76 in FIG. 12a. This pulley will support the cable but allows it to move lengthwise without undue pull on the column 4 in the direction parallel to the axis of the cable. In such arrangement the cables must be firmly held in the lengthwise direction at predetermined intervals, as for example, at the station or stop location.

While I have described several embodiments of my invention it will be understood that various modifications can be made therein by those skilld in the art which are within the true spirit and scope of my invention.

I claim:

1. In a system for moving a vehicle over the earth along a course while carried on and moving along a flexible elongate member, supported by support means, means defining a reference path, means for generating a signal indicative of the displacement between said vehicle and said path and means for moving said vehicle in response to said signal so as to make said displacement a preselected value.

2. In a system for moving a vehicle along a course while carried on and moving along first and second elongate members provided respectively with first and second mechanisms adapted to alter the location of said first and second members, means defining a reference path, first sensing means adapted to generate a first signal characteristic of first direction displacement between said vehicle and said path, second sensing means adapted to generate second signal characteristic of second direction displacement between said vehicle and said path and means for actuating said first and second mechanisms in response to said first and second signals so as to maintain said first direction and said second direction displaements at preselected values.

3. A system for transporting a car over the terrestrial surface comprising a flexible elongate member supported by suspension means, said car being carried on, and moving along said member by carrying means and conveyed along a travel path in proximity of said member, means defining a predetermined travel path independent of said terrestrial surface for said car in proximity of said course, sensing means for sensing the displacement between said car and said path and adapted to generate a signal in response to said displacement and control means responsive to said signal operative to maintain said displacement at a preselected value.

4. In a transport system as set forth in claim 3 wherein said control means is operative to vary the characteristics of said carrying means.

5. In a transport system as set forth in claim 3 wherein said control means is operative to vary the characteristics of said suspension means.

6. In a transport system 5 set forth in claim 3 wherein said sensing means is a seismometer.

7. In a transport system as set forth in claim 3 wherein aid sensing means is an inertial guidance sensor.

8. A transportation system including a moving vehicle carried on and moving along a flexible elongated member suspended from support points, comprising:

a. extendible support means between said vehicle and said support points;

b. means generating a guidance signal indicative of the displacement between said vehicle and a reference path of travel; and

0. means for varying the length of said extendible means in response to said guidance signal.

9. A transportation system according to claim 8 wherein said extendible support means is positioned between said elongated member and said support points.

10. A transportation system according to claim 8 wherein said extendible support means is positioned between aid vehicle and said elongated member.

11. A transportation system for a moving vehicle carried on and moving along a flexible elongate member, comprising:

means generating a guidance signal indicative of the displacement between said vehicle and a reference path of travel; and

means applying variable supporting force to said elongate member in response to said guidance signal thereby maintaining a preselected displacement between said vehicle and said reference path. i i 

1. In a system for moving a vehicle over the earth along a course while carried on and moving along a flexible elongate member, supported by support means, means defining a reference path, means for generating a signal indicative of the displacement between said vehicle and said path and means for moving said vehicle in response to said signal so as to make said displacement a preselected value.
 2. In a system for moving a vehicle along a course while carried on and moving along first and second elongate members provided respectively with first and second mechanisms adapted to alter the location of said first and second members, means defining a reference path, first sensing means adapted to generate a first signal characteristic of first direction displacement between said vehicle and said path, second sensing means adapted to generate second signal characteristic of second direction displacement between said vehicle and said path and means for actuating said first and second mechanisms in response to said first and second signals so as to maintain said first direction and said second direction displacements at preselected values.
 3. A system for transporting a car over the terrestrial surface comprising a flexible elongate member supported by suspension means, said car being carried on, and moving along said member by carrying means and conveyed along a travel path in proximity of said member, means defining a predetermined travel path independent of said terrestrial surface for said car in proximity of said course, sensing means for sensing the displacement between said car and said path and adapted to generate a signal in response to said displacement and control means responsive to said signal operative to maintain said displacement at a preselected value.
 4. In a transport system as set forth in claim 3 wherein said control means is operative to vary the characteristics of said carrying means.
 5. In a transport system as set forth in claim 3 wherein said control means is operative to vary the characteristics of said suspension means.
 6. In a transport system s set forth in claim 3 wherein said sensing means is a seismometer.
 7. In a transport system as set forth in claim 3 wherein said sensing means is an inertial guidance sensor.
 8. A transportation system including a moving vehicle carried on and moving along a flexible elongated member suspended from support points, comprising: a. extendible support means between said vehicle and said support points; b. means generating a guidance signal indicative of the displacement between said vehicle and a reference path of travel; and c. means for varying the length of said extendible means in response to said guidance signal.
 9. A transportation system according to claim 8 wherein said extendible support means is positioned between said elongated member and said support points.
 10. A transportation system according to claim 8 wherein said extendible support means is positioned between said vehicle and said elongated member.
 11. A transportation system for a moving vehicle carried on and moving along a flexible elongate member, comprising: means generating a guidance signal indicative of the displacement betweeN said vehicle and a reference path of travel; and means applying variable supporting force to said elongate member in response to said guidance signal thereby maintaining a preselected displacement between said vehicle and said reference path. 